In the recent past, prior to the instant invention, "energy-storing" prosthetic devices built for and marketed in this field have taken the simple form illustrated in FIG. 7 of the drawings wherein a strong and flexible graphite-composite plate is shaped to provide an ankle portion "b", and a toe portion "c", and is affixed to a smaller plate to provide a heel portion "d".
The energy-storing capacity of the device, illustrated in FIG. 7, is intrinsic to the graphite-composite material utilized in its construction. However, the simple design of the unit is found to be inadequate in its inability to approximate the range of motion possible in a human ankle.
More multi-directional flexibility in the ankle-portion of the device coupled with a more stable basal portion of the device is needed to fulfill the requirements of an active user.
Although ball and socket joints may be suggested for an artificial ankle structure, more and complicated elements may have to be incorporated in an attempt to effect the desired control for an active user or even for a relatively sedentary user.